1. Field of the Invention
The present invention relates, in general, to power distribution and distribution systems, and more particularly, to a modular power distribution unit for use in distributing power within the limited space of an equipment cabinet or rack, such as a computer equipment rack or a data storage cabinet.
2. Relevant Background
In the computer industry, mass storage systems and other computer systems typically include numerous multi-shelf cabinets or racks each holding multiple devices or encloses, such as servers, disk drives, and other computer devices. These racks or rack systems are ideal for modular projects and are designed to accept standard sized devices having relatively standard power requirements and communication connections. Generally, the outer case includes an aluminum or steel framework fitted with covers and a series of connectors at the rear from which the devices or modules derive their power and exchange communication signals. The individual modules include a supporting chassis or housing that slides into the rack and is supported on guides, such as clip-in glides. Racks and rack systems are inherently flexible but are often expensive which drives users and rack makers to efficiently use space within the rack or cabinet.
Each rack or cabinet typically only has a limited amount of space that is defined by or urged into shelves. The shelves or shelf locations are configured to allow a device enclosure or module or other components to be plugged into and supported within the rack. Typical rack configurations call for 14 shelves although more shelves may be provided such as up to 24 or more shelves. If shelves are arranged vertically, a typical cabinet may have 14, 24, 32, or some other number of shelves that each occupy a certain amount of rack space, such as 3 retma(U) which is a standard mounting unit increment.
In practice, such as data centers, data storage, and the like, the racks are often densely packed with devices, such as servers each requiring a primary power supply and a backup power supply for redundancy. For example, one arrangement uses up to 14-3U server enclosures in a rack requiring up to 28–750 watt power supplies. In another rack configuration, 21-2U servers are installed in a rack with 42–500 watt primary and redundant power supplies. A major challenge facing rack and equipment designers is how best to serve dense equipment users so as to provide increased power distribution while efficiently using the space within the rack to reduce cable clutter and connection and supply confusion. In other words, it is desirable to reduce the amount of space required for power distribution units (PDUs) (e.g., typically, a plurality of electrical receptacles to which electrical plugs of power cords can be connected and which are supplied by an inlet A/C power source) and power cords from the PDUs to the devices on the rack shelves to thereby free up rack U-space for more modules or enclosures.
Existing forms of power distribution require large volumes of cabinet or rack space as numerous PDUs are provided and often mounted in the rack that reduces the available shelves or U-space for computer or other desired components. For example, current PDU support requirements often call for as many as four to six 24 amp PDUs per rack, which leads to some rack configurations being limited when a maximum number of PDUs have been installed in the rack In addition to the space required for the PDUs, large volumes of rack space may be required for the large number of power cords and other devices required to connect the PDUs to the individual devices or loads on the shelves. Often, an enclosure or device is located on a shelf which is relatively distant from the closest PDU which requires a long power cord to be snaked through the rack to the enclosure or device. The number of the cables and PDUs increases deployment complexity and can cause connection problems and mistakes. Additionally, after installation is completed, later expansions or modifications to the rack and power distribution arrangements are difficult to successfully implement.
Hence, there remains a need for an improved method and system for distributing power within an equipment rack or cabinet that requires less U-space, reduces the number and lengths and cost of connecting power supply cords used in racks (Le., provides improved cable or cord management), is simple to customize, to install, and upgrade or later modify, and reduces the total deployment cost.